Patent Literature 1 describes a gallium nitride based semiconductor light-emitting device provided on a GaN substrate having a nonpolar plane. It describes a number of planes for the primary surface of the GaN substrate as follows. The primary surface of the GaN substrate is: a {11-20} plane, a {1-100} plane, or, a plane inclined in the range of −5 degrees to +5 degrees from the {11-20} plane or the {1-100} plane. Furthermore, the primary surface of the GaN substrate has a plane that is inclined at an off angle θ (where 0°≦θ≦10°) with respect to either the {11-20} plane or the {1-100} plane. Furthermore, the primary surface of the GaN substrate has a {11-20} plane, a plane inclined in the range of −5 degrees to +5 degrees from the {11-20} plane, or a plane that is inclined at an off angle θ of not more than 10 degrees with respect to the {11-20} plane.